Participants were evaluated on two scales: Environmental stimulation -- such as "child has toys that teach color" at age 4, and "child has access to at least 10 appropriate books" at age 8 -- and parental nurturing, such as "parent holds child close 10-15 minutes per day" at age 4, and "parents set limits for child and generally enforce them" at age 8.
Researchers looked at whether cortical thickness in young adulthood could be predicted by the earlier environmental stimulation and parental nurturing measurements. Greater cortical thickness in childhood is associated with poor outcomes such as autism, Avants explained. Later in adolescence, relatively reduced cortical thickness is linked to higher IQ and other mental processes.
From this study, Farah and colleagues suggested that environmental stimulation at age 4 predicts cortical thickness in the late teenage years, but parental nurturing did not appear to be linked.
The study hasn't been published yet. Their next step: Understanding how brain differences emerge, starting with infants.
With the first weeks and months of life, Farah and colleagues believe they will find differences in the brains of infants of low socioeconomic groups. Led by Hallam Hurt of the Children's Hospital of Philadelphia, the group has been scanning the brains of infants as young as 1 month old.
If they do find brain differences in babies associated with socioeconomic status, this could be attributable to a number of factors, including stress, nutritional factors, health care, environmental toxins and second-hand smoke.
A better future, a better brain
As enthusiastic as Farah and colleagues are about the work they are doing, obtaining funding is always a challenge -- hence, the grant proposal she was working on last week. When she first started this work around 2000, she was met with skepticism about looking at poverty's effects on the brain, she said, as if her research would equate poverty with brain disease or worse.
In a tongue-in-cheek way, Avants said he and Farah have discussed defining a "disease" with all the symptoms of poverty and its effects on development. "Then it might be very easy to get funding," he said.
There are far fewer children with autism than there are poor children in the United States, for example, but autism as a condition gets more attention from the science community than the neurological implications of poverty, he said.
"One of the most important things Martha is doing is pushing this, maintaining awareness on the long-term effects of poverty on outcomes," he said.
In the meantime, the research is still developing. There some puzzling results that don't yet make sense, Farah said, and it's hard to say at this point precisely what aspects of social class cause brain differences.
There is no large consortium of scientists working on problems of the brain and social class, either. On a broader scale, there are relatively few studies done about the brain and cognition using participants from low socioeconomic backgrounds.
"Most cognitive neuroscience is done with college sophomores in universities that are wealthy enough to have an imaging center," Farah said. "We are looking at a tiny slice of humanity."
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